Frequently Asked Questions
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    What about freezing?

    Every Alabama solar water heater has to be protected from freezing.  Solar thermal collectors are protected
    from freezing by one of two methods.  Both methods are called "closed loop" systems because the potable
    water does not flow through the collectors.  Instead, a "heat transfer fluid" is used along with a heat exchanger.

  1. Drain-back systems use water as the heat transfer fluid.  A small tank that holds about ten gallons of water and
    the heat exchanger is located in a conditioned space near the hot water storage tank.  Water is pumped from
    this tank through the collectors when heat is available.  When the sun sets or the system has collected as much
    heat as it can hold, the pump shuts off and the water drains back into the drain-back tank.  Drain-back systems
    are extremely efficient and almost maintenance free.
  2. The second system uses a non-toxic glycol antifreeze mixture that stays in the collectors.  This system is slightly
    less efficient and requires a little more maintenance than drain-back systems.  Regardless, there are times
    when the closed-loop glycol system is the best choice.

    There are sometimes other reasons for selecting a glycol system over a drain-back.  We'll have to consider your
    specific needs.  However, you can take comfort in knowing that your water heater will not freeze, even if the
    thermometer is reading single digits.
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